George Jetson, Meet the Sequel

By DANNY HAKIM

Published: January 9, 2005

THE Sequel is totally cool.

General Motors' latest hydrogen car prototype, called the Sequel, will be unveiled today at a press preview of the North American International Auto Show here. It is a car unlike any other and a glimpse of a possible, very different, automotive future. Most important, it runs on a hydrogen fuel cell, so its only tailpipe emission is water vapor, not the smog-forming pollutants and greenhouse gases that come out of gasoline-powered cars.

So why do environmental groups see the Sequel not as a panacea for cars' environmental shortcomings but as G.M.'s latest Trojan horse?

G.M. has trotted out impressive hydrogen-fueled cars before -- most recently the Sequel's predecessor, the Hy-wire. G.M. says it will theoretically be able to mass-produce fuel cell vehicles affordably by 2010 -- even though most competitors, which are also working on the technology, say it will be decades before such vehicles are viable.

And G.M. hardly screams green in the present. In the 2003 model year, the average fuel economy of G.M.'s cars and trucks fell to its lowest point in two decades. And the company has lobbied vigorously to block more stringent fuel regulations and has taken major roles in lawsuits against California's antipollution rules.

''There's no sign by General Motors that they have any inclination to act in the here and now,'' said David Doniger, policy director of the climate center of the Natural Resources Defense Council and a senior Environmental Protection Agency official in the Clinton administration.

Lawrence Burns, G.M.'s vice president for research and development, says G.M. makes many vehicles that are the most fuel-efficient in their class. It also makes many laggards, though, and its Hummer is Detroit's least fuel-efficient brand. But Mr. Burns says the fuel cell can end gasoline's grip on the industry.

''It could flat-out reinvent the automobile,'' he said in a recent interview. ''The environmentalists who think we're doing a head fake with this, either they're not listening to that part of the story or believe we've made it up. But the engineer in me says this is the greatest opportunity certainly in my career to truly come up with a better machine.''

Hydrogen fuel cell cars are not to be confused with hybrid electric cars, which were brought to the United States in the late 1990's by Honda and Toyota. A hybrid vehicle uses an electric motor alongside an internal combustion engine. Hybrids work pretty much like regular cars; drivers just have to go to the gas station a bit less often. And hybrids are already here: more than 80,000 were sold in America last year.

By contrast, a fuel cell represents an entirely new way of propelling a car. A single cell is a waferlike device that separates hydrogen atoms into electrons and protons, using the electrons to generate a current. The byproduct of the process is water vapor, formed when the leftover hydrogen protons are combined with oxygen from the air. A whole stack of these wafers -- 372 in the Sequel -- is required to generate enough power for a car. The Sequel's stack is stored in a steel case a bit larger than a VCR.

Fuel cells have been around for more than a century. They provided power for the lunar landers, conveniently spitting out water for astronauts to drink. Back in the days of lunar landers -- in the 1960's and 70's, when G.M. was dominant among American corporations -- the company built the first automotive fuel cell prototype. The system, however, was clunky and filled an entire van, called ''Electrovan,'' and was sort of a cross between the Hindenburg and Scooby Doo's Mystery Machine.

More recently, G.M. and other automakers have been able to wedge fuel cell systems under the hoods of conventional vehicles, and the companies are convinced that riding on top of a tank of compressed hydrogen is no less safe than riding on top of a tank of gasoline.

But G.M. also sees the technology as an opportunity to reimagine the automobile. All of the Sequel's essential components are housed in a surfboardlike platform under the car. While G.M. has displayed a similar idea at previous shows, the Sequel has been engineered to be a real car that complies with crash test regulations.

G.M. says it has been able to double the range of fuel cell vehicles in less than three years, to the point that the Sequel can travel 300 miles before refueling, making it the first hydrogen prototype that can go as far between fill-ups as a conventional car.

At a glance, the Sequel looks like a modern blend of an S.U.V. and a station wagon. Because the fuel cells used in cars would operate at about 180 degrees Fahrenheit, they require more cooling and thus about twice the radiator space of a conventional car, so honeycombed radiator surfaces are nestled around the front taillights, in the back and on the sides.

Under its skin, if it is not quite ''The Jetsons,'' the Sequel is at least a car for the digital age. Braking, steering and other control systems will operate electronically, more like the systems on a modern jet than the mechanical and hydraulic controls on a conventional automobile -- though there will be backup conventional braking and steering controls. As a result, the Sequel will have far fewer moving parts than a normal car.